Heater vaporizer element support



Jan. 24, 1961 P. ALEXANDER HEATER VAPORIZER ELEMENT SUPPORT 3Sheets-Sheet 1 Filed March 3, 1959 FIG- 2 FIG. 3

PAUL ALEXANDER INVENTOR ATTORNEYS Jan. 24, 1961 P. ALEXANDER HEATERVAPORIZER ELEMENT SUPPORT 3 Sheets-Sheet 2 Filed March 3, 1959 FIG. 6

FIG- 4 FIG- 5 PAUL ALEXANDER INVENTOR BY o SW ATTORNEYS Jan. 24, 1961 P.ALEXANDER 2,969,448

HEATER VAPORIZER ELEMENT SUPPORT Filed March 5, 1959 3 Sheets-Sheet 3 ST A A 7%) 71 1 FIG. 8 7O 70 PAUL ALEXANDER INVENTOR v 6 VJW FIG 9 BY44,, WQDM ATTORNEYS HEATER VAPORIZER ELEMENT SUPPORT Paul Alexander,Princeton, N.J., assignor to Continental Can (lompany, Inc., New York,N.Y., a corporation of New York Filed Mar. 3, 1959, Ser. No. 796,800

9 Claims. (Cl. 219-49) This invention relates to the art of vapordeposition of materials in vacuum, and is more particularly concernedwith the support and electrical connection of vaporizing elements and amethod of employing the same.

The vaporizing element is employed for the purpose of raising thedeposition material to a high temperature, i.e. to above itsvaporization or sublimation temperature at the low pressure or vacuumemployed during the deposition operation. Such elements can be heated byconduction of electrical current therethrough, wherewith the electricalresistance causes the development of heat in the element.

It is known to make these elements of substances such as carbon ortungsten, possibly with protective coatings of materials resistant tothe solvent or chemical action of the deposition material. When thedeposition material is aluminum, for example, aluminum carbide is formedat the interface of contact of the molten metal with the carbon, andsuch corrosion reduces the crosssection of the carbon and progressivelybuilds up a mass of aluminum carbide on it. When tungsten is employed alike corrosion occurs by dissolution. In such cases of corrosion, it isnecessary to adjust the voltage being applied to the element, in orderto assure an amperage which will give an 1 R heating effect appropriateto maintain the deposit material at the requisite temperature forevaporation. In large scale operations, several heating and vaporizingelements are employed; and therewith individual variations of theelements make it difficult to operate each element at an optimumcondition for its service.

When coatings of less-soluble or less-reactive materials are employed,e.g. as set out in my prior patents and patent applications, thedegradation of the elements is delayed so that hours of continuousservice of elements in vacuum deposition is possible. Such elements aremore brittle than simple carbon or tungsten elements, and great care isneeded in mounting and connecting them for the electrical current flowtherethrough.

This need of care in mounting is even greater with refractory carbidesof many elements and with noncarbon heating elements of refractoryborides, nitrides or silicides. This is true for such compounds of thetransitional metal elements of groups IV, V and VI of the periodicsystem, which are commonly referred to as hard metals.

These elements are brittle at room temperatures and at the temperaturesof 1400 to 1500 degrees C. which are employed during vacuum depositionof metals; noting that such temperatures are still low as compared withthe melting points of the compounds; and heat shock and irregularheating can cause breakage during the initial heating up to operatingtemperature and during the operation period.

According to one object of the present invention, a satisfactorymounting and connection is eltected by employing supports for the endsof the vaporizing element which have pivoted parts which carryconductive mem- States Patent bers for engaging the element withpermissive relative movement during the heating of the element.

Another object is the provision of such a support having a bottomsurface for mechanical and electrical engagement with the upper surfaceof a bus bar, and comprising two parts interconnected to move about anupright pivot axis, with resilient means to cause the parts to engageand maintain engagement with the element.

A further object is the provision of such a support having two partspivoted to move relatively about an upright axis, one of the partshaving a bottom surface for mechanical and electrical engagement withthe upper surface of a bus bar, and the other part being mounted on saidfirst part, and resilient means to cause the parts to engage andmaintain engagement with the element.

A further object is the provision of such a support having two partspivoted to move relatively about an upright axis, contact memberscarried by said parts for engaging the vaporizing element at limited andtransversely alined areas of the upright side walls thereof, andresilient means for causing the parts to move relative to one anotherabout said axis and therewith engage and maintain engagement of thecontact members with the element.

With these and other objects as features in view, as will appear in thecourse of the following description and claims, illustrative embodimentsof the invention are shown on the accompanying drawings, in which:

Fig. l is a conventionalized upright cross-sectional view of a vacuumdeposition chamber, showing the employment of vaporizer elementsupports;

Fig. 2 is a plan View, on a larger scale, of one form of a vaporizerelement support according to this invention;

Fig. 3 of Fig. 2,

Fig. 4 is a plan view of another form of support;

Fig. 5 is an upright section substantially on line 55 of Fig. 4;

Fig. 6 is a plan view of a third form of support.

Fig. 7 is an upright sectional view, corresponding to Fig. l, of amodified employment of the supporting blocks of Figs. 2-6;

Fig. 8 is a plan view, on a scale smaller than that of Fig. 2, showing aclamping device.

Fig. 9 is a side elevation of the parts in Fig. 8, with parts omittedfor clearness.

Fig. 1 shows a conventionalized form of vacuum chamher for metalevaporation and deposit upon a substrate. The chamber 1 has a conduitconnection 2 to a vacuum pumping system. The illustrative substrate is aweb 3 which is unwound from a supply roll 4, passed across the chamberabove the vaporizer elements, and then rewound on a driven take-up roll5. Pairs of copper bus bars 1%, 11 extend horizontally along thechamber, the bars of each pair being of opposite potentials during theoperation. Mounting blocks 12 for vaporizer elements are provided forcontact with and support upon the bus bars 10, 11; and are present inpairs, with one block of each pair resting on one bus bar, and the otherblock on the other bus bar. These bus bars are of large section forpassage of high amperage currents without excessive loss by electricalresistance and illustratively have fiat tops so that the elementmountings can be seated by gravity thereon, and moved therealong ifnecessary for producing vapor in such local concentrations that auniform or a predetermined varied depth of coating can be deposited onthe substrate. The blocks 12 are illustratively in pairs, with eachblock of a pair in contact with a respective bus bar 10 or 11: and thepair provide mounting for a vaporizer element, as described hereinafter.Supply rolls 6 of the material to be vaporized and is an upright sectionsubstantially on line 3-3 asoaeee deposited, such as aluminum in wireform, deliver the material through guides 7 to the vaporizer elements20.

In Figs. 2 and 3 a first form of gripping supports for a vaporizerelement is shown as engaged with the ends of such an element 2%. The twosupports are identical and rest by their weights on the bus bars lid,ill. Each support has a first jaw member Eli and a second jaw member 22,which have ears 23 engaged by a pivot 2 Extension arms 25 have reducedends fitted in holes in the jaws and are held in place by the bindingscrews 26. At the outer or free ends, these arms 2 illustratively havethe pins 27 for entering the ends of and guiding a compression coilspring 23 which acts to force the ends of the arms apart and therewithcause the surfaces of the jaws to move toward one another. These jawshave recesses so extending parallel to the bottom surfaces of the jawsand spaced upward therefrom. Blocks 31 of copper are tightly fitted inthese recesses 34?, and have open channels 32, likewise parallel to thebottom surfaces of the jaws. Coil springs 33 of conductive material,having a higher melting point than the operating temperature, aremounted and supported in the channels, and in turn bear against the sidesurfaces of the vaporizer element 20.

In Figs. 4 and 5, a second form is shown in which the jaw blocks 41 41are connected by a pivot 42 and have the arms 25 with pins 44 for thecompression spring 23. In this illustrative form, the blocks id, if havethe pivot 42 located at a non-symmetrical point. The jaws have alinedapertures 45 for receiving the contact members 46 which are held thereinby the set screws 4'7, and engage the element 20. The arms 25 and spring2 3 are active for moving the contact members 46 toward one another, forgripping the vaporizing element 2% at alined areas of the oppositeupright walls thereof.

in Fig. 6, the jaw blocks 50, 51 are illustrated as having ears joinedby a pivot 52 located between the bodies of the blocks, and a spring 23to rock them so that the contact members 53, are moved toward oneanother, to clamp upon the element 2%. These members 53 are shown ashaving stems which fit in the alined holes 54 of the jaw blocks, andenlarged heads which are pressed down upon the jaw blocks, around theholes, incidental to the action of the spring 28 and the heating of theparts during service. As before, the contact with the vaporizing element2d is at alined areas of the opposite upright walls.

The contact members as, 53 may be of copper. In each case, the contactmember has a truncated conical head so that the original engagement isfor a restricted area.

When a heater-vaporizer element Zli becomes defective and is removed,the supports may be prepared for new use, by replacing the old element20 with a new one, and replacing the coils 33 of Figs. 2 and 3, or themembers as, S3 of Figs. 4 to 6. After several replacements of the coils33 in Figs. 2 and 3, it is usually desirable to replace the groovedblocks 31.

In each form of construction, the assembly of two of the support memberswith a vaporizer element 24 may be prepared to advance. When one or moreexisting elements are noted, as defective, the depositing operation canbe stopped, the vacuum released, and the chamber opened. The defectiveelement or elements can be quickly lifted out, and new assembliessubstituted. The chamber can be closed, the vacuum restored, the busbars energized and the metal feeding started: and thus there is littledown time consumed in the change-over.

As the current begins to flow, there initially is thermal expansion ofthe heater element 253. In the form of Figs. 2 and 3, the coils 33 canthen yield; and in the forms of Figs. 4 to 6, the ends of the contactmembers 46, 53 can yield; noting that in each case, the spring 28assures mechanical gripping and hence electrical conduction, by rockingthe blocks about their pivot cona; nection. As the heating continues,during the course of operation, the material of the coils 33 and themembers 46, 53 may become softer, but a satisfactory mechanical supportof the element 2d at a point above the bus bar, and electricalconduction thereto, is maintained by the spring.

It is also feasible to employ the structures with the elements 2%positioned at an angle to the horizontal, instead of horizontally as inFig. 1. Thus in Fig. 7, the bus bars 1t 11 are shown at differentelevations, and in pairs at either side of a substrate 65, which may bea metal strip entering the chamber 61 through a top seal 62 shown inconventionalized form as a pair of rollers, and leaving the chamberthrough a like seal 63 at the b ttom. Therewith the elements 2% at thetwo sides of the strip es may be operated to give coatings of like ordifferent thicknesses at the two surfaces thereof.

In such cases, the pro-assemblies of Figs. 4 to 6 are especiallyadvantageous as the contact members 46, 53 provide pivot connections toelement Zti, so to speak, so that the assembly can be bent as necessaryfor positioning the supports on the illustrated level tops of the busbars, with the elements 2b extending slantwise there between.

It is also feasible to employ supports of relatively lesser mass orweight, and to hold these against shifting by clamps. Thus in Figs. 8and 9, the supports S, T on the bus bar 1% are held by a clamp plate 7%resting on a jaw block of each, with the clamp or draw bolt 71 passingthrough the clamp plate and through a hole 72 of the bus bar N, with aspring 73 interposed between the lower face of the bus bar and a washer74. The wing nut 75 is then adjusted so that the clamp plate 7d exerts alight pressure upon the blocks which holds them to the bus bar butpermits them to slide along it under forces arising by thermal expansionof the heater element. Therewith an assured regularity of electricalcontact and conduction between the blocks and the bus bar is assured,and the sliding for relief of stresses can occur even with the minordeposits of metal upon the bus bars, as often occurs. The actiontherefore avoids the thermal shocks to the heater elements which canoccur when a block moves in response to heating and loses its regularityof contact, and thus a lesser current flows; followed abru tly by a goodcontact engagement at which a higher current passes and the heatingcauses a thermal shock to the element and breakage may occur. In addition to the protection against thermal shock to the element itself, thisclamping assures the regular heating of the element which gives aregular evolution of vaporized metal and thus a regular deposit on thesubstrate. it will be understood that Fig. 8 shows the use of a platefor engaging two blocks each being part of a sup port for a respectiveheater element; and that the arrangement may be repeated between otherpairs of blocks engaging the same bus bar.

The jaw blocks 21, 22, 4t), 41, 50, 51 can be of copper with their lowersurfaces conformed to the bus bar surface. It has been foundsatisfactory to have the upper bus bar surfaces as horizontal planes,Wherewith the bottoms of the blocks are flat.

It will be understood that the illustrative forms are not restrictive,and that the invention can be employed in many Ways within the followingclaims.

What is claimed is:

l. A clamp and support structure for a vaporizing heater element foremployment in vacuum deposition, comprising a pair of bus bars havingflat upper surfaces, a pair of blocks having fiat lower surfaces forconductive engagement with a respective bus bar for gravitationalsupport and movable thereon, an upright pivot hingedly connecting theblocks, so that parts of the blocks can be moved toward and from theside surfaces of the heater element, and a resilient element engagedwith the blocks for causing said parts to engage the said side surfacesof the heater element with permissive relative rocking.

2. A clamp and support structure as in claim 1, in which said parts areprovided with contact pins held thereby for engaging the heater elementat aligned points at opposite upright sides thereof whereby the heaterelement may pivot about the axis provided by the pins.

3. A clamp and support structure as in claim 2, in which the pins haveconical ends, and means are provided on the block for fixing thedistances between the ends of the pins in the absence of a vaporizerelement.

4. A clamp and support structure as in claim 2, in which each pin has acylindrical stern received in a bore of the respective said part, and anenlarged head with a truncated conical end for engaging the heaterelement, said enlarged head being adapted to bear against the surface ofsaid part around the mouth of the bore therein in conductive relation tosaid surface.

5. A clamp and support structure for a vaporizing heater element foremployment in vacuum deposition, comprising a pair of bus bars havingfiat upper surfaces, a pair of blocks having surfaces for conductiveengagement with a respective bus bar for gravitational support andmovable thereon, an upright pivot hingedly connecting the blocks atpoints thereof intermediate the respective ends, and a coil springlocated and acting against one end of each block whereby to cause theother ends thereof to move under resilient pressure into engagement withopposite upright side surfaces of the heater element with permissiverelative rocking.

6. A clamp and support structure for a vaporizing heater element foremployment for vapor deposition comprising a bus bar for conductingcurrent to said heater element having a flat upper surface, a pair ofblocks having flat lower surfaces for gravitationally resting on thesaid bus bar surface and movable thereon, a pivot hingedly connectingthe blocks at intermediate points thereof, a coil spring located andacting between ends of the blocks to cause the other ends to move towardopposite upright sides of the heater element and establish electricalconduction thereto, a clamp plate engaging an upper surface of a block,a draw member engaging the plate and extending through the bus bar, anda spring acting against the bus bar and effective to hold the plateunder resilient pressure against the block with permitted slidingmovement of the block between the bus bar and the plate.

7. A structure as in claim 6 in which the draw memher is threaded andhas a nut thereon effective for varying the holding efiect of thespring.

8. A clamp for a vaporizing heater element for employment in vacuumdeposition, comprising a pair of blocks having surfaces for conductiveengagement with an electrically charged surface, a pivot hingedlyconnecting the blocks, so that parts of the blocks can be moved towardand from the heater element, said blocks having grooves at said parts,contact coil springs located in the grooves for engaging andestablishing conduction between the blocks and a multiplicity of pointsat opposite sides of the heater element when the said parts are movedtoward the heater element, and a resilient element for causing saidparts to move toward the heater element.

9. A clamp as in claim 8, in which each block has a removable conductiveblock seated therein at said part thereof, the removable block having asaid groove therein.

References (Iited in the file of this patent UNITED STATES PATENTS496,775 Burton et al. May 2, 1893 1,256,951 Thomson Feb. 19, 19182,005,752 Pfanstiehl June 25, 1935 2,671,828 Traver Mar. 9, 19542,679,545 Kistler May 25, 1954 2,780,718 Mullen Feb. 5, 1957

